In an earlier contribution to this discussion, Richard
wrote:
I've traced the wiring and it's he

http://homepage.ntlworld.com/richard...RY/boiler.html

I want to know, is this circuit a correct one? Are there any errors
in it?
I don't understand the thing with the two black wires from the boiler.
I've disconnected, and never made a note of which black wire went
where. I thought it did not matter. since both are black.

Boiler is VOKERA "Pinnacle 16".
--------

Vokera "Pinnacle 16" Schematic

If I have not made a mistake, this is how my VOKERA "Pinnacle 16" was
wired up.

In the Installation and Service Instructions, an example of the "S
Plan System" is given. It is not like this schematic.


Your schematic and the S-Plan diagram in the boiler installation manual are
*essentially* the same - it's just that the detailed implementation is
slightly different.

The essential characteristic of S-Plan is that each actuator motor is fed
from the programmer via its respective thermostat, and the auxialliary
contacts are wired in parallel - with one side having a permanent live feed
and the other side connected to the boiler's switched live demand. Both
diagrams show this - the only difference being where the permanent live feed
comes from. In yours, it comes from the heating control switch and in
Vokera's it comes form M7/2 on the boiler which - if you look at Fig 31 in
Section 8.1 of the manual, is almost certainly permanently live.

In the Service Instructions, the two switches inside the motorised
actuators (Danfoss HPA2) are wired in parallel, but both wires
(orange - grey) just go into the boiler (to M7, pins 2 & 3).


In both cases, the two orange wires are connected to M7/3 - which is pretty
certainly the demand for heat.

The boiler has 5 wires going into it, 3 for mains (L N E) and two
wires - both coloured black.

Here you see that the two switches inside the actuators are both in
parallel, but live at one end, and the other (orange wires) goes to a
black wire into the bolier.


Yes, as above, this must go to M7/3


On this schematic, tracing the other black wire from the boiler, it
goes onto pins 2 & 5, of the Danfoss SET 3A timer. Pin 1 (Water ON)
goes to the cylinder (water) stat, then through the water actuator
motor, then to Neutral. Pin 4(Heater ON) goes through the Room Stat, then
through
the heater actuator motor, then to Neutral.

There is no link connecting the Live wire, in the timer, to any of the
pins numbered 1 to 6. Presumably the Live potential is coming from the
boiler -out of the black wire.


That bit's a complete mystery to me! That other black wire is almost
certainly a live feed to the switching contacts in the programmer - but I
haven't a clue why the main live feed to the programmer isn't used instead.
Where on the boiler does that black wire connect?


Is the schematic I've drawn out correct?

Probably, but the feed to the progammer remains a mystery.

What I don't understand is these black wires. There is no way to tell
which black wire should be connected to what. I believe you must
connect the right black wire to the switches or the thermostat.


The black wire which is connected to the two orange wires in the actuators
definitely needs to go to M7/3 - there is no doubt about that. As far as the
other one is concerned, I would be inclined to get rid of it and connect 2
and 5 to L internally in the timer.



If you get rid of the tank, you will only have one zone - so you can get rid
of the motorised zone valves too. If you do that, the output from the room
stat will then need to go directly to boiler demand M7/3. [You can probably
get rid of the bypass circuit too, as long as there will always be at least
one radiator open].

Having said all that, getting rid of the tank still seems a strange thing to
be doing. Don't you need any hot water for bathing/showering, etc.? If you
*do*, where are you going to get it from?
--
Cheers,
Roger
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